There's No Doubt that Gwen Stefani and Gavin Rossdale seem like a happy Hollywood couple.

But in an interview with Elle UK, as excerpted by PopSugar, Stefani admits her relationship with the Bush frontman hasn't always been picture perfect.

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"I've been with Gavin for 14 years, and let's face it, that is a huge accomplishment," she says. The two first met in 1995 on tour, started dating two years later and finally married in 2002. They have two sons together-- Kingston, 4, and Zuma, 2. Rossdale also learned in 2004 of his daughter, Daisy Lowe, now 22, from his brief relationship with singer-turned-designer Pearl Lowe.

PHOTOS: Check out Kingston, Zuma and other celeb kids

"I feel so proud (of our relationship)-- it hasn't been the easiest journey," she admits.

"I wear make-up every single day," the star says. "I like to wear make-up for Gavin and I don't feel energized until I've put it on, then I'm ready to go."

She says her famously fit body is "a daily struggle" and confides, "I work out five days a week. I can't imagine not doing it."

PHOTOS: Gwen's incredible abs

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